1. Field of the Invention
The invention relates to a separator mill, and more particularly, fluidized-bed opposed jet mills configured as separator mills, and to the arrangement of components therefore.
2. Description of the Prior Art
Fluidized-bed opposed jet mills generally consist of a cylindrical grinding container set on a vertical axis, wherein gas jets are provided in the lower part of the grinding container. These gas jets are directed in opposite directions in such a manner that the material to be ground in the grinding container is sucked into the airflow and accelerated by the airflow so that the material is crushed on impact as the particles of the material to be ground collide with each other.
In order to remove already-ground fine material from the mill, while leaving material that has not yet been sufficiently ground in the mill, the upper part of the grinding container contains a separating device. The separating device is usually embodied as a separator that uses centrifugal force, wherein the particles that are smaller than the critical separation size are transported inward into the rotating bucket wheel of the separator and separated in this manner, while the particles that are larger than the critical separation size are thrown off the rotating bucket wheel and remain inside the grinding container.
This type of a separator mill is known, e.g., from DE 33 38 138 C2. It is embodied as a fluidized bed jet mill with a grinding chamber that is free of fixtures for directing the gas jets used for the grinding process, wherein a nozzle with a gas jet that is ejected vertically upward and that is used both to grind and to fluidize the material to be ground in the grinding chamber is provided in the bottom area of the grinding chamber. The grinding chamber is completely filled with material up to a level so that material to be ground and gas exit from the bed of material as a slow speed column. This column is used to feed a separator, which is located above the surface of the bed of material and operates independent of the jet emerging from the bottom nozzle.
In this arrangement, a certain number of additional jet nozzles that open towards the bed of material are positioned below the surface of the bed of material. The openings of these nozzles are distributed around a circle that is coaxial with the axis of the bottom nozzle and within a plane that is perpendicular to the axis of the bottom nozzle. The axes of these nozzles intersect each other at a point on the axis of the bottom nozzle below the plane of the nozzle openings.
The separating device in this design is located in the upper part of the grinding container and rotates about a vertical axis. The separator wheel operates based on the principle of centrifugal force and separates material that has been ground sufficiently fine from the material to be ground and discharges it from the grinding container via a finely ground material discharge opening arranged above the separator wheel. Furthermore, a mounting and driving device for the rotating separating wheel is positioned above the discharge opening for finely ground material.
Conventional fluidized bed opposed jet mills have an overall structure of the grinding container and an arrangement of the corresponding components that are designed entirely in consideration of industrial engineering conditions. However, there is a growing demand for machines designed according to industrial engineering conditions which can also be easily assembled and disassembled by the user and which must be easily accessible for thorough cleaning.
This is especially true for the pharmaceutical industry and for toner production wherein production is based on batch production. Only small amounts of product are ground, and then, shortly thereafter, entirely different products are ground in the same mill. For example, when changing to a toner product of a different color, or when switching between pharmaceutical products with different effects, it is absolutely mandatory to clean the entire machine thoroughly so that residual amounts of the previous product will not contaminate the next product to be ground.
Cleaning of conventional separating mills is complicated and time consuming. In particular, there is a high risk that there will still be small residual amounts of the previous product in the machine even after cleaning.
It is therefore the task and object of the invention to improve a fluidized-bed opposed jet mill with a separator so that it is easily accessible and it can be cleaned in a simple manner and without much effort. This task is solved, and object is achieved, by the apparatus of the present invention. Further additional and advantageous embodiments can be apparent from the following detailed description of the present invention.
The fluidized-bed opposed jet mill according to the invention provides a separator arrangement that forms one component from the mounting device and the actuator and that is attached to the grinding container in a detachable manner. In this arrangement, the component can move relative to the grinding container by means of kinematic devices, in such a way that the separator wheel can be removed from the grinding container upwards through the discharge opening for the finely ground material. The discharge opening for the finely ground material remains attached to the grinding container.